Mamma Mia! will surely please Abba's legion of fans; a story-theater adaptation of Ovid is all wet.

The Italian exclamation "Mamma mia!" usually expresses a not entirely pleasurable surprise or a not wholly unenjoyable shock. Emotionally rather than literally, it translates as "Holy cow!" Which is pretty much my reaction to the musical Mamma Mia!

Why the Italian title when the show takes place on a Greek island? Well, because that is the title of one of the preexistent songs of the Swedish rock group Abba, whose string of unrelated disco hits forms the musical's score. Then why not set it in Italy? To erase the obvious similarity to the 1968 movie Buona Sera, Mrs. Campbell, in which three ex-GIs find they have been paying child support to the same local belle, played by Gina Lollobrigida. But Catherine Johnson, the British book author, stoutly denies any debt to the film, and wanted to emphasize her independence by setting the action in Greece. Besides, the inspiration to do a show using Abba's hits occurred when Björn Ulvaeus -- with Benny Andersson the group's male half -- caught the London production of Grease.

Now, Buona Sera was no masterwork, yet it was believable for three GIs to shack up with the same willing beauty during the finale of World War II's Italian campaign. But who is this American woman, Donna Sheridan, on a small Greek isle who carried on with one British and two American tourists in rapid succession circa 1980 -- when there was no war -- had a daughter by one of them, but stayed on as a taverna-keeper and raised her daughter all by herself? It does not compute. Johnson, hired by the producer Judy Craymer to build a show around these songs so many have grown up on, came up with this improbable and lackluster musical book. It is rather like the case of someone who finds a button in the street and has a suit made to match. With the difference, though, that a button allows much more freedom to the tailor than twenty-odd Abba songs allow the bookwriter.

The jerry-built result predictably leaves the show dependent on the songs, the production values, and the performers. The plot now has Donna's daughter, Sophie, getting married and, wanting to find her father, inviting all three men she finds in her mother's diary to the impending nuptials, unbeknown to Mom. All three show up, as do, for other reasons, the two female backup singers who, long ago, performed in Donna's trio. Since this meets most people's preposterousness quota, enough of plot summary, and on to more relevant matters.

I did not grow up on Abba's music, but I didn't mind the songs Andersson and Ulvaeus wrote for the musical Chess, which were purposefully created for that show. Abba's music must have something to it: How can more than 350 million worldwide record sales be wrong? (Or can they?) The lyrics are good enough for Swedes writing in English; most of them cannot be heard over the din, anyway. If you happen to have a couple of spare eardrums, be sure to bring them along. That said, I found the score neither unbearable nor something I'd miss if I never heard it again.

As for the actors, all -- except the chief comic (saddled with admittedly poor material) -- fall somewhere between adequate and agreeable. Mark Thompson's sets and costumes are serviceable, with perhaps a few too many scuba-diving suits. Anthony Van Laast's choreography and Phyllida Lloyd's staging serve their purpose. I would not discourage anyone interested from attending Mamma Mia!. But I wouldn't encourage the doubtful, either.

Ovid's Latin poetry in the Metamorphoses is considerable, which makes the myths of transformation they deal with, however well-known, not uninteresting. But take away the poetry, add some cutesily modern touches, turn the whole thing into story theater (a bastard genre that has long since outlasted its welcome), and what have you got, especially if your performers range from seven undistinguished to three repellent?

That is what Mary Zimmerman with her company from Chicago, where story-theater -- half recitation, half acting out -- originated, has contrived. She sets it, startlingly but incongruously, in and around a swimming pool, which could more worthily have served a revival of the musical Wish You Were Here.

Mamma Mia! Broadway musical based on the music of Abba.Metamorphoses Staged by Mary Zimmerman.